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SCHEMATICCURRENT · v1.0.0DIAG-BETA-RATIO

Beta Ratio Measurement — Upstream / Downstream Particle Count

Illustrates the fundamental principle of the Beta ratio (filtration ratio) as defined in ISO 16889. Upstream particles of all sizes enter the filter element; only those below the rated efficiency cut-off pass through to the downstream side. The ratio of upstream to downstream particle counts at a given size defines the Beta ratio, which directly quantifies filtration efficiency.

Beta Ratio Measurement — ISO 16889Schematic showing upstream particle count (Nᵤ) before the filter element and downstream particle count (Nd) after, with the beta ratio formula β = Nᵤ/Nd and efficiency equation E(%) = (1 − 1/β) × 100.UPSTREAMNuupstream countFILTERELEMENTDOWNSTREAMNddownstream countβ = Nᵤ / NdE(%) = (1 − 1/β) × 100ISO 16889
Left zone shows upstream contaminated fluid with many particles of varying sizes (large orange circles, medium particles, fine particles). Central zone is the filter element shown as a hatched rectangle. Right zone shows downstream clean fluid with only a few fine particles that passed through. Formula β = Nᵤ/Nd and efficiency E(%) = (1 − 1/β) × 100 are shown at bottom.

GOVERNING STANDARDS

ISO 16889
ISO 11171

ELIMFILTERS TECHNOLOGIES

NANOFORCE™
SYNTRAX™
SYNTEPORE™

APPLICABLE SYSTEMS

Hydraulic Protection
Lubrication Protection
Fuel Cleanliness Protection

REVISION METADATA

Versionv1.0.0
Statuscurrent
Last Reviewed2026-07-08
Next Review2027-07-08

RELATED ENGINEERING ARTICLES

→Beta Ratio
→Iso 16889
→Filter Media Science
→Fluid Cleanliness
→Filter Media Engineering

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